Structures of isopropylidene nucleoside derivatives - implications for ribose ring flexibility under external cyclic constraints

Crystal structures of six isopropylidene nucleoside derivatives are described. The results show that, under external cyclic constraints, the ribose assumes a variety of unusual conformations. In those compounds which possess a base-to-sugar cyclization through the C(4′) atom, the furanose pucker is predominantly C(4′)-endo, O(4′)-exo. The possible relevance of the sulphur geometry in two of the compounds to certain structural aspects of the action of the enzyme thymidylate synthetase is also pointed out.

Morphological diversity of ruminal bacteriophages from sheep and cattle

Large numbers of bacteriophages (2 x 10(7) to 1 x 10(8)/ml) were present in ruminal fluid from sheep and cattle. Twenty-six distinct types were identified and placed in three morphological groups; several phages possessed unusual structural features. The large numbers and diversity of phages observed indicates a possible role in bacterial lysis and hence in the population dynamics of the ruminal bacteria.

Morphological and molecular diversity of Colletotrichum spp. causing pepper spot and anthracnose of lychee (Litchi chinensis) in Australia

Since the 1980s a new disease has been affecting Australian lychee. Pepper spot appears as small, black superficial lesions on fruit, leaves, petioles and pedicels and is caused by Colletotrichum gloeosporioides, the same fungus that causes postharvest anthracnose of lychee fruit. The aim of this study was to determine if a new genotype of C.gloeosporioides is responsible for the pepper spot symptom. Morphological assessments, arbitrarily-primed PCR (ap-PCR) and DNA sequencing studies did not differentiate isolates of C.gloeosporioides from anthracnose and pepper spot lesions. The ap-PCR identified 21 different genotypes of C.gloeosporioides, three of which were predominant. A specific genotype identified using ap-PCR was associated with the production of the teleomorph in culture. Analysis of sequence data of ITS and -tubulin regions of representative isolates did not group the lychee isolates into a monophyletic clade; however, given the majority of the isolates were from one of three genotypes found using ap-PCR, the possibility of a lychee specific group of C.gloeosporioides is discussed.

Dark-energy constraints and correlations with systematics from CFHTLS weak lensing, SNLS supernovae Ia and WMAP5

Aims We combine measurements of weak gravitational lensing from the CFHTLS-Wide survey, supernovae Ia from CFHT SNLS and CMB anisotropies from WMAP5 to obtain joint constraints on cosmological parameters, in particular, the dark-energy equation-of-state parameter w. We assess the influence of systematics in the data on the results and look for possible correlations with cosmological parameters. Methods We implemented an MCMC algorithm to sample the parameter space of a flat CDM model with a dark-energy component of constant w. Systematics in the data are parametrised and included in the analysis. We determine the influence of photometric calibration of SNIa data on cosmological results by calculating the response of the distance modulus to photometric zero-point variations. The weak lensing data set is tested for anomalous field-to-field variations and a systematic shape measurement bias for high-redshift galaxies. Results Ignoring photometric uncertainties for SNLS biases cosmological parameters by at most 20% of the statistical errors, using supernovae alone; the parameter uncertainties are underestimated by 10%. The weak-lensing field-to-field variance between 1 deg2-MegaCam pointings is 5-15% higher than predicted from N-body simulations. We find no bias in the lensing signal at high redshift, within the framework of a simple model, and marginalising over cosmological parameters. Assuming a systematic underestimation of the lensing signal, the normalisation increases by up to 8%. Combining all three probes we obtain -0.10 < 1 + w < 0.06 at 68% confidence ( -0.18 < 1 + w < 0.12 at 95%), including systematic errors. Our results are therefore consistent with the cosmological constant . Systematics in the data increase the error bars by up to 35%; the best-fit values change by less than 0.15.

Morphological changes in the conjunctiva, episclera and sclera following short-term miniscleral contact lens wear in rigid lens neophytes

PURPOSE To quantify the influence of short-term wear of miniscleral contact lenses on the morphology of the corneo-scleral limbus, the conjunctiva, episclera and sclera. METHODS OCT images of the anterior eye were captured before, immediately following 3h of wear and then 3h after removal of a miniscleral contact lens for 10 young (27±5 years) healthy participants (neophyte rigid lens wearers). The region of analysis encompassed 1mm anterior, to 3.5mm posterior to the scleral spur. Natural diurnal variations in thickness were measured on a separate day and compensated for in subsequent analyses. RESULTS Following 3h of lens wear, statistically significant tissue thinning was observed across all quadrants, with a mean decrease in thickness of -24.1±3.6μm (p<0.001), which diminished, but did not return to baseline 3h after lens removal (-16.9±1.9μm, p<0.001). The largest tissue compression was observed in the superior quadrant (-49.9±8.5μm, p<0.01) and in the annular zone 1.5mm from the scleral spur (-48.2±5.7μm), corresponding to the approximate edge of the lens landing zone. Compression of the conjunctiva/episclera accounted for about 70% of the changes. CONCLUSIONS Optimal fitting miniscleral contact lenses worn for three hours resulted in significant tissue compression in young healthy eyes, with the greatest thinning observed superiorly, potentially due to the additional force of the eyelid, with a partial recovery of compression 3h after lens removal. Most of the morphological changes occur in the conjunctiva/episclera layers.

Managing flexible work arrangements in small not-for-profit firms: The influence of organisational size, financial constraints and workforce characteristics

Small, not-for-profit organisations fulfil a need in the economy that is typically not satisfied by for-profit firms. They also operate in ways that are distinct from larger organisations. While such firms employ a substantial proportion of the workforce, research addressing human resource management (HRM) practices in these settings is limited. This article used data collected from five small not-for-profit firms in Australia to examine the way one significant HRM practice – the provision and utilisation of flexible work arrangements – operates in the sector. Drawing on research from several scholarly fields, the article firstly develops a framework comprising three tensions in not-for-profits that have implications for HRM. These tensions are: (1) contradictions between an informal approach to HRM vs. a formal regulatory system; (2) employee values that favour social justice vs. external market forces; and (3) a commitment to service vs. external financial expectations. The article then empirically examines how these tensions are managed in relation to the specific case of flexible work arrangements. The study reveals that tensions around providing and accessing flexible work arrangements are managed in three ways: discretion, leadership style and distancing. These findings more broadly inform the way HRM is operationalised in this under-examined sector.

Archaean crustal evolution in eastern Finland : New geochronological and geochemical constraints from the Kuhmo terrain and the Nurmes belt

This thesis summarises the results of four original papers concerning U-Pb geochronology and geochemical evolution of Archaean rocks from the Kuhmo terrain and the Nurmes belt, eastern Finland. The study area belongs to a typical Archaean granite-greenstone terrain, composed of metavolcanic and metasedimentary rocks in generally N-S trending greenstone belts as well as a granitoid-gneiss complex with intervening gneissic and migmatised supracrustal and plutonic rocks. U-Pb data on migmatite mesosomes indicate that the crust surrounding the Tipasjärvi-Kuhmo-Suomussalmi greenstone belt is of varying age. The oldest protolith detected for a migmatite mesosome from the granitoid-gneiss complex is 2.94 Ga, whereas the other dated migmatites protoliths have ages of 2.84 2.79 Ga. The latter protoliths are syngenetic with the majority of volcanic rocks in the adjacent Tipasjärvi-Kuhmo-Suomussalmi greenstone belt. This suggests that the genesis of some of the volcanic rocks within the greenstone belt and surrounding migmatite protoliths could be linked. Metamorphic zircon overgrowths with ages of 2.84 2.81 Ga were also obtained. The non-migmatised plutonic rocks in the Kuhmo terrain and in the Nurmes belt record secular geochemical evolution, typical of Archaean cratons. The studied tonalitic rocks have ages of 2.83 2.75 Ga and they have geochemical characteristics similar to low-Al and high-Al TTD (tonalite-trondhjemite-dacite). The granodiorites, diorites, and gabbros with high Mg/Fe and LILE-enriched characteristics were mostly emplaced between 2.74 2.70 Ga and they exhibit geochemical characteristics typical of Archaean sanukitoid suites. The latest identified plutonic episode took place at 2.70 2.68 Ga, when compositionally heterogeneous leucocratic granitoid rocks, with a variable crustal component, were emplaced. U-Pb data on migmatite leucosomes suggest that leucosome generation may have been coeval with this latest plutonic event. On the basis of available U-Pb and Sm-Nd isotopic data it appears that the plutonic rocks of the Kuhmo terrain and the Nurmes belt do not contain any significant input from Palaeoarchaean sources. A characteristic feature of the Nurmes belt is the presence of migmatised paragneisses, locally preserving primary edimentary structures, with sporadic amphibolite intercalations. U-Pb studies on zircons indicate that the precursors of the Nurmes paragneisses were graywackes that were deposited between 2.71 Ga and 2.69 Ga and that they had a prominent 2.75 2.70 Ga source. Nd isotopic and whole-rock geochemical data for the intercalated amphibolites imply MORB sources. U-Pb data on zircons from the plutonic rocks and paragneisses reveal that metamorphic zircon growth took place at 2.72 2.63 Ga. This was the last tectonothermal event related to cratonisation of the Archaean crust of eastern Finland.

A note on sampling chironomids for RNA-based studies of natural populations that retains critical morphological vouchers

The rapid uptake of transcriptomic approaches in freshwater ecology has seen a wealth of data produced concerning the ways in which organisms interact with their environment on a molecular level. Typically, such studies focus either at the community level and so don’t require species identifications, or on laboratory strains of known species identity or natural populations of large, easily identifiable taxa. For chironomids, impediments still exist for applying these technologies to natural populations because they are small-bodied and often require time-consuming secondary sorting of stream material and morphological voucher preparation to confirm species diagnosis. These procedures limit the ability to maintain RNA quantity and quality in such organisms because RNA degrades rapidly and gene expression can be altered rapidly in organisms; thereby limiting the inclusion of such taxa in transcriptomic studies. Here, we demonstrate that these limitations can be overcome and outline an optimised protocol for collecting, sorting and preserving chironomid larvae that enables retention of both morphological vouchers and RNA for subsequent transcriptomics purposes. By ensuring that sorting and voucher preparation are completed within <4 hours after collection and that samples are kept cold at all times, we successfully retained both RNA and morphological vouchers from all specimens. Although not prescriptive in specific methodology, we anticipate that this paper will assist in promoting transcriptomic investigations of the sublethal impact on chironomid gene expression of changes to aquatic environments.

Institutional constraints on altruism in the formation of a venture idea

This thesis is about the social orientation of new venture ideas and how the degree of social orientation is influenced by the entrepreneur's level of altruism, by industry norms, and by nonprofit work experience. Potential entrepreneurs were asked to generate new venture ideas based on 3D-printing and their ideas were rated for degree of social orientation. It was found that while greater altruism leads to more socially-oriented venture ideas, the influence of altruism on the venture idea is constrained by the profit-maximization norm that is prevalent in most industries.

Symmetries and constraints in generalized Hamiltonian dynamics

A general analysis of symmetries and constraints for singular Lagrangian systems is given. It is shown that symmetry transformations can be expressed as canonical transformations in phase space, even for such systems. The relation of symmetries to generators, constraints, commutators, and Dirac brackets is clarified.

Determination of optimal trajectory under design constraints for a satellite launch vehicle

An optimal pitch steering programme of a solid-fuel satellite launch vehicle to maximize either (1) the injection velocity at a given altitude, or (2) the size of circular orbit, for a given payload is presented. The two-dimensional model includes the rotation of atmosphere with the Earth, the vehicle's lift and drag, variation of thrust with time and altitude, inverse-square gravitational field, and the specified initial vertical take-off. The inequality constraints on the aerodynamic load, control force, and turning rates are also imposed. Using the properties of the central force motion the terminal constraint conditions at coast apogee are transferred to the penultimate stage burnout. Such a transformation converts a time-free problem into a time-fixed one, reduces the number of terminal constraints, improves accuracy, besides demanding less computer memory and time. The adjoint equations are developed in a compact matrix form. The problem is solved on an IBM 360/44 computer using a steepest ascent algorithm. An illustrative analysis of a typical launch vehicle establishes the speed of convergence, and accuracy and applicability of the algorithm.

Optical, dielectric and morphological studies of sol-gel derived nanocrystalline TiO2 films

Nanocrystalline TiO2 films have been synthesized on glass and silicon substrates by sol-gel technique. The films have been characterized with optical reflectance/transmittance in the wavelength range 300-1000nm and the optical constants (n, k) were estimated by using envelope technique as well as spectroscopic ellipsometry. Morphological studies have been carried Out using atomic force microscope (AFM). Metal-Oxide-Silicon (MOS) capacitor was fabricated using conducting coating on TiO2 film deposited on silicon. The C-V measurements show that the film annealed at 300 degrees C has a dielectric constant of 19.80. The high percentage of transmittance, low surface roughness and high dielectric constant suggests that it can be used as an efficient anti-reflection coating on silicon and other optical coating applications and also as a MOS capacitor.